Folks with dual processors might appreciate seeing that both cpus are doing their share. In the "GrabBag" subdirectory of the Applications directory, there's a graphical cpu monitor that show's the activity of both processors.

If you want to see both cpus constanlty busy download the text-only version of seti@home and run 2 versions (from different directories). Use the "-nice 20" flag and you won't notice any loss in performance since the OSX kernel will sacrifice seti@home performance in order to keep everything else speedy.